Abstract: Volume II/19 is a supplement to the previous published volumes II/4, II/6 and II/14. The slight change in the title of the series reflects current trends in the applications of spectroscopic methods. The four volumes II/4, II/6, II/14 and II/19 together comprise a comprehensive collection of critically evaluated data on constants of free molecules obtained by classical and modern spectroscopy which have appeared in the literature until 1989/1990. The present subvolume 19d1 provides critically evaluated data which have appeared in the literature up to 1991/92. Subvolume II/19d3 provides a substance index for all volumes II/4, II/6, II/14 and II/19.

Abstract: Volume II/19 Molecular Constants mostly from Microwave, Molecular Beam and Sub-Doppler Laser Spectroscopy is a supplement to the earlier volumes II/4, II/6, and II/14. The slight change in the title reflects current trends in the applications of spectroscopic methods. Together, the four volumes collect all the critically evaluated data published up to 1989/90 on constants of free molecules obtained by classical and modern spectroscopy. Volume II/19 is divided into four parts to record the growing number of investigations, especially in the microwave and millimeter wave regions, where modern techniques like Fourier Transform Microwave Spectroscopy have made new objects of interest such as molecular complexes and clusters accessible to study. Subvolume II/19c contains tables for diamagnetic molecules giving further spectroscopic parameters: quadrupole coupling constants, potential barriers, and data from Stark and Zeeman effect measurements.

Abstract: Volume II/24 presents the spectroscopic data on diamagnetic and paramagnetic molecules as well as on molecular ions and radicals up to date considering the publications up to and partly including 1997. The spectroscopic information collected in this volume has been obtained principally from gas phase microwave measurements. Volume II/24 is a supplement to volumes II/4, II/6, II/14, and II/19 and is planned to appear in five subvolumes, the last of which will contain the substance index taking into account all molecules worked at since 1967 in the volumes mentioned and will provide cross references to and between all tables of these. The present subvolume II/24A contains the general introduction and tables of rotational and centrifugal distortion constants of diamagnetic diatomic, linear and symmetric-top molecules, i.e. data which roughly specifies the frequencies of the rotational transitions of these types of rotors.